1. Field of the Invention
The present invention relates to packaging and more particularly to a packaging system and method wherein articles are packaged in successive container portions of packaging webs with the container portions closely conformed to the articles and wherein individual packages are separated from the web without any adverse effects on portions of the web being loaded.
2. Prior Art
The Article Patent describes a packaging web or container strip formed by a chain of interconnected container detachable bag-like portions. The container portions each define a load opening in one face and a transverse seal line defining a closed end of each container portion. The other face of each container is connected to a contiguous container portion along a preformed line of weakness so that the container portions are relatively easily detached from the web.
The Machine Patents disclose packaging apparatuses for feeding such a web or strip of container portions to a loading station at which successive container portions are opened, loaded, closed, sealed and severed from the web. The closure is effected by a pair of relatively movable closure members which engage the open end region of the container portion, to clamp the faces of the container portion together. The closure is then secured, typically by heat sealing the faces together.
In some packaging applications, it is desirable to confine a quantity of air in the sealed containers to prevent the contents from being crushed or damaged during shipment. In other packaging applications, it is desirable to deflate the containers before they are sealed to minimize the volume of the sealed containers. While the apparatus of the Machine Patents are well adapted to confine a quantity of air in containers as they are closed and sealed, such apparatuses do not address the problem of deflating containers prior to closure.
The Deflation Patent describes a resilient pressure pad including a plurality of resilient elements which are individually compressible against a loaded container portion to conform the container portion to the shape of its contents and in so doing expel air from the container portion prior to its closure.
Where relatively long articles are packaged, the use of such a pressure pad to deflate a loaded container portion requires that the pressure pad be quite lengthy. Moreover, where the container portions are relatively long and narrow, a lengthy pressure pad brought into engagement with the full side area of the container portion may tend to close its open end before the expulsion of air from regions near the closed end of the container portion.
Furthermore, when apparatus of the character described in the Machine Patents is used to package articles such as flexible sheet paper material, fabrics, and so forth which must be hand-loaded, the packaging process can be cumbersome and time consuming. Since the apparatus utilizes a single station for loading, closing and sealing, the operator must wait until one sealing operation is completed before a subsequent container portion is positionable for loading. Loading the subsequent container portion must be accomplished by stuffing the article into the container portion between the closure members. Even though the closure members are separated, their presence adjacent the load opening tends to impede the loading procedure. The container portion being loaded is usually unsupported and this, along with the obstruction created by the closure members substantially slows the loading process. If the subsequent container portion is to be deflated, this step must occur between the loading and sealing steps. Thus, the difficulties in hand loading along with the deflation operation increases the cycle time of the apparatus appreciably.
A problem which is frequently encountered in packaging applications is the need to isolate web portions in one location or work station from forces which are applied to web portions in a nearby location or work station. For example, where a loaded container portion is severed from the end of a web by exerting forces on the loaded container portion for tearing from the web along the line of weakness between the container portion and the web, the tearing force can be transmitted along the web to other lines of weakness remote from the loaded container portions. If adequate precautions are not taken to prevent transmission of such forces along the web, two or more container portions will be severed from the web simultaneously.